I have a 98 Mach1 that is running hot. When doing normal trail riding ( 40 - 45 MPH ) the temp. runs about halfway, but as soon as I get on the gas the temperature quickly rises and will go into the red if I don't back off. I have had this sled for a few years and have alwys been able to ride at higher speeds without any problems. I am not really sure what it could be. Possibly the thermostat? Any suggestions would be greately appreciated.